Sidereal Time and Solar Time

I have started teaching a Math course in Astrology and while most of my students accept at face value the steps to construct a chart without a computer, others really challenge me. My latest student really struggled with why Sidereal time had to be reconciled with Solar time in order to define the angles of the chart and the inner house cusps. I really struggled to come up with an explanation that was accessible to an audience that may not have a strong mathematical back ground. After about two weeks of driving myself insane, I think I’ve come up with something that explains the differences between Sidereal Time and Solar Time. This understanding can be the starting point to what is not a difficult process (creating the chart) but it is a time consuming process with many, many steps. Here we go:

There are three distinct movements associated with the Earth.The daily rotation of the earth on its axis, the Earth’s orbit around the Sun, and the rotation of the axis itself. These movements are measured by Sidereal and Solar time.
Solar time is relative to the Sun, while Sidereal Time is measured by calculating the the Earth’s movements relative to a distant star.

What is Sidereal Time?
Sidereal time is a way of measuring time based on the Earth’s rotation relative to a distant star, rather than the Sun.
A Sidereal day is the time it takes for the Earth to complete one full rotation relative to the stars. (23 hr 56’ 04”).
A Sidereal year is the time it takes the Earth to complete one orbit (360°) around the Sun, again, relative to the stars.(366.256 days).

What is Solar Time
Solar time is a way of measuring time based on the Earth’s rotation relative to the Sun.
A Solar day is the time it takes to complete one rotation on its axis, relative to the Sun.
The earth must rotate slightly more than 360° to return to the same spot because the Earth is orbiting at the same time it is rotating, and is 24 hr 00” 00” in length.
A Solar year is the time it takes to complete one orbit around the Sun, 365.25 days.
This is why we have a leap year every 4 years.

Why does the Ephemeris “reset” sidereal time to 0 every September?

The daily notations of Sidereal Time in the American Ephemeris increase by slightly less than 4 minutes each day. This is measuring how much of the orbit around the Sun the Earth completes each day (4’ = 1°), not the rotation of the Earth on its axis. (23hr56’04”)

In the American Ephemeris, Sidereal time resets to 0 when the Vernal Equinox, (the point when the Sun crosses the celestial equator) also crosses the observer’s meridian. This is a universally accepted convention, much like how our calendar year begins on Jan 1st.

The Precession of the Equinox (the rotation of the axis itself)

In the context of the Precession of the Equinox, this September to September period is also referred to as a Sidereal Day. It is a measurement of the rotation of the Earth’s axis, caused by the rotation of the Earth. Similar to the spinning a top, the axis itself describes a slight arc. By extending this arc onto the celestial equator from the North Pole, the arc eventually completes one 360 degree rotation. This takes approximately approximately 25,600.

71 years to move 1°, = 26,000 (23 56′ 04″ Sidereal days)
26,000 days x 360° = 9,360,000 days (360° rotation of the axis)
9,360,000/366.256 = 25,556 Sidereal years (25,600)

Aspects and Orbs, Oh My!

Astrology has a language all its own, and depending on your genre of Astrology, each component, whether it be a planet, a house, or a sign, has pretty specific keywords associated with it. Even the aspects themselves are divided into easy or hard and have ease of flow or varying degrees of tension.

So as an astrologer the first stage of your development requires you to learn that language, and it can take time. The meanings of each component have to make their way from one part of your brain to the next so they become muscle memory. Much like multiplication tables in elementary school, they become intuitive, knee-jerk responses. Hopefully the transition is more enjoyable than rattling off multiplication tables.

Once the meanings are fixed, it becomes so much easier to navigate the complex art of blending two or more together in a meaningful way. It’s one thing to understand how Venus in Virgo in the 9th house (travel planner), is very different from Venus in Aries in the 10th (controlling boss, (but she’s so nice!)). The next hurdle is to place that Venus in Virgo in the 9th house in aspect to, let’s say Saturn in Pisces in the 8th.

Let’s say ol’ Saturn in Pisces, is struggling trying to figure out what’s not working. Saturn is uncomfortable in the mutable Water sign, not quite ready to go with the flow that Pisces demands. The 8th is not just taxes and super responsibility though, it is a house of deep intimacy, the dissolution of ego and the becoming one with another is also a very big part of the 8th house. These themes tie in well with Pisces, dissolution of boundaries. Saturn has great survival skills and convinced of the journey will follow through.

Now what is the aspect? Well with one in the 8th and the other in the 9th we’ll go with the obvious, the sextile. A sextile is two planets 60° apart, but once you take in a possible orb of 7° or even 10°, there’s some wiggle room, and a sextile in two adjoining houses is not rare. The sextile brings understanding and awareness of the needs of each planets.

The 8th house themes of deep intimacy and transformation do combine well with the 9th house embracer of all things new, and a willingness to change. Virgo and Pisces find common ground, both mutable and fluid in their own ways also embracing newness. Venus finds joy and Saturn brings the determination to stay the course, to not give up.

Rectification

Rectification is a time consuming process, and it will stretch every astrological muscle you possess. It is a great way to test your technical abilities and merge them with the untangible intuitive sense that astrologers must also possess.

Many professional astrologers don’t do rectifications, mostly because of the amount of time it takes combined with nebulous results. 12 astrologers are guaranteed to give 12 diifferent results. The proof, they say, is in the pudding and the rectification process must include a verification process, in order to validate the chart you have chosen.

By using solar returns, and continuous testing of the rectified chart, its validity can be ascertained, but this also takes time. The general theory is that if the rectified chart matches past events in the client’s life, the chart can be used to match current and future events.

An unexpected benefit of working with a client on their rectification is the effect it has on the client. As you move through the events and the charts surrounding those events, the client relives the experiences, bringing up forgotten emotions, and reviewing their life through a lens of maturity that was not available to them at the time.

It is a cathartic process for the client, and well worth the hours of effort to find “the one”.